08 October 2020

How much sh*t is in our waters?

Finally, NEA is providing public weekly water quality assessments. Previously only provided once a year.
from NEA's Beach Short-term Water Quality Information

This water quality information is based on the levels of enterococcus bacteria in the water.

Enterococcus bacteria comes from feces of humans and warm-blooded animals. Possible sources include human sewerage released untreated into the water, and untreated waste from live-stock farms. 

Levels of enterococcus bacteria indicate the possible presence of disease-causing bacteria/viruses. These can sicken people who swim, dive or do water sports; with possible diseases of the skin, eyes, ears and respiratory tract. Eating fish or shellfish harvested from waters with fecal contamination can also result in human illness. 

What are possible sources of enterococcus bacteria in the northern shores?

There are lots of fish farms off our northern shores. I wonder how sewerage from humans who live on the fish farms are treated? The green lines in the NEA website include Pasir Ris Beach (opposite Pulau Ubin).
From Google Earth, you can see the many 'dots' indicating floating fish farms in the waters between Pasir Ris Beach and Pulau Ubin (circled in yellow). 
How many humans live on these farms? How many farms are in the waters off Pasir Ris Beach? According this Straits Times article in Apr 2020,  Singapore has 110 licensed sea-based fish farm sites, of which 108 are in the Johor Strait. Let's assume half are in the East Johor Strait, that would be about 50 farms off Pasir Ris Beach. Say each farm  has 5 people=250 people. Or equivalent to 50 flats each with a 5-member family; with 4 flats per floor (e.g., a point block), this would be a 12-storey point block. 

Here's more about the issues.

According to the NEA media release dated 7 Oct 2020:

The water quality information is based on the enterococcus bacteria (EC) levels of the water.When water quality is in the Band 1 (Normal) range, the public can continue with their normal primary contact water activities. If the water quality is in the Band 2 (Elevated) range, beachgoers should exercise caution. In particular, children, the elderly, and the immunocompromised should reduce primary contact water activities. When the water quality enters the Band 3 (High) range, all beachgoers should minimise primary contact water activities.

The public need not be unduly concerned if certain stretches of the beach go into the Band 2 (Elevated) or even the Band 3 (High) range for a particular week, as the enterococcus levels are transient in nature and the beach water is continuously flushed and mixed by currents.

In addition to the current yearly water quality data for the seven popular recreational beaches, beachgoers will now have access to weekly water quality information and broken down to smaller sections of the seven recreational beaches.

What are enterococcus bacteria? Where do they come from? These were not explained in the NEA media release. So here's more information.

From the EPA Environmental Protection Agency, USA website:

What are enterococci?


Enterococci are bacteria that live in the intestinal tracts of warm-blooded animals, including humans, and therefore indicate possible contamination of streams and rivers by fecal waste.

Sources of fecal indicator bacteria such as enterococci include wastewater treatment plant effluent, leaking septic systems, stormwater runoff, sewage discharged or dumped from recreational boats, domestic animal and wildlife waste, improper land application of manure or sewage, and runoff from manure storage areas, pastures, rangelands, and feedlots.

There are also natural, non-fecal sources of fecal indicator bacteria, including plants, sand, soil and sediments, that contribute to a certain background level in ambient waters and vary based on local environmental and meteorological conditions.

Why is it important to evaluate enterococci?

Enterococci are indicators of the presence of fecal material in water and, therefore, of the possible presence of disease-causing bacteria, viruses, and protozoa. These pathogens can sicken swimmers and others who use rivers and streams for recreation or eat raw shellfish or fish. Other potential health effects can include diseases of the skin, eyes, ears and respiratory tract. Eating fish or shellfish harvested from waters with fecal contamination can also result in human illness.

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